Previous studies on speech tempo in Hungarian have revealed that it is getting faster in general and that it is an age group related variable, too. In this paper, the authoress studied the speech rate and articulation rate of secondary school pupils, a group of speakers generally assumed to speak fast. She tried to find out what relationship obtains between the tempo and quality of their speech and how all that relates to comprehensibility. Articulation rate and speech rate values, as well as the types, number, and length of utterance-internal (silent and filled) pauses were established for two age groups (15 and 18-yearolds). She collected and classified the phenomena characterising their articulation, looked at their frequency of occurrence, and analysed the pronunciation variants arising due to fast tempo. The results confirmed the effect of age on tempo in this narrower age range, too. The faster speech of older pupils co-occurred with significant shortening of their silent pauses. Increasing speech tempo resulted in sound omissions, syllable omissions and various sound replacements, as well as in massive shortening of vowel durations. Articulatory inaccuracies due to fast tempo and the resulting variant pronunciations primarily occurred in content words, therefore they can lead to difficulties in comprehension and to communication deficits.